Stent graft

ABSTRACT

Some embodiments are directed to a stent graft comprising a first stent graft having a first and a second stent and a first and a second inner graft supported by the first stent, and an outer graft. The second inner graft can be spaced apart from the first inner graft so that a portion of the first stent is not covered by either the first inner graft or the second inner graft. A first and second portion of the outer graft can be attached to the first stent, the outer graft being unsupported by the stent between the first and second portions so as to form a fillable space between the outer graft, the first inner graft, and the second inner graft. Some embodiments further comprise a second stent graft deployable within the inside of the first stent graft to sealingly cover the uncovered portion of the first stent.

PRIORITY INFORMATION AND INCORPORATION BY REFERENCE

This application is a divisional of U.S. patent application Ser. No.12/844,266, filed on Jul. 27, 2010, which claims priority benefit under35 U.S.C. §119(e) of U.S. Provisional Application 61/228,938 filed Jul.27, 2009 and U.S. Provisional Application 61/248,105 filed Oct. 2, 2009,all of which applications are hereby incorporated by reference as iffully set forth herein.

BACKGROUND OF THE DISCLOSURE

1. Technical Field

The present disclosure relates to endoluminal vascular prostheses andmethods of placing such prostheses, and, in one application, toendoluminal vascular prostheses for use in the treatment of Type IIendoleaks.

2. Background

Stent grafts can be used for the endovascular treatment of aorticdisease including aneurysms and dissections. The purpose of the stentgraft is generally to isolate the diseased portion of the aortic wallfrom the aortic blood pressure and prevent further dilatation or ruptureof the diseased portion of the aortic wall.

FIG. 1 shows an infrarenal abdominal aneurysm. The aorta 4 is enlargedbelow the renal arteries 2 a, 2 b and above the iliac arteries 3 a, 3 b.The enlarged aorta has formed an aneurysm sac 1. Pairs of lumbararteries 5 a, 5 b branch from the aorta 4 in the region of the aneurysmsac 1.

FIG. 2 shows a bifurcated stent graft 10 placed in the aorta 4 toexclude the aneurysm sac 1 from the arterial blood pressure. The stentgraft 10 creates a proximal seal distal to the renal arteries 2 a, 2 band a distal seal 3 a, 3 b in the iliac arteries. An incomplete sealcreates leakage flow from the aorta 4 into the aneurysm sac 1 and intothe lumbar arteries 5 a, 5 b. A leak at the proximal or distal seal ofthe stent graft 10 is referred to as a Type I endoleak. A leak betweenoverlapping components of the stent graft system 1 is referred to as aType III endoleak. A leak through the covering of the stent graft isreferred to as a Type IV endoleak. Type I, III, and IV are influenced bythe specific design features of the stent graft 10.

There also exists a type of endoleak that is independent of the stentgraft 10. The leak is created by pressure differences in the lumbararteries 5 a, 5 b. FIG. 3 illustrates a leakage flow from a first pairof lumbar arteries 5 a to a second pair of lumbar arteries 5 b whereinthe blood pressure in the first pair of lumbar arteries 5 a is greaterthan that in the second pair of lumbar arteries 5 b. This type of leakis referred to as Type II endoleak.

Current stent graft systems do not address the issue of Type IIendoleaks. Type II endoleaks are present in a considerable number ofpatients after stent graft placement. These endoleaks can potentiallycause continuing dilatation and even rupture of the aneurysm in somepatients.

Various strategies have been developed to manage Type II endoleaks. Ingeneral, patients are monitored and their aneurysms are imaged routinelyto ensure stabilization of the aneurysm. In case of persistent Type IIendoleaks associated with aneurysm dilatation, interventions arerecommended to embolize the endoleak. Coils or fast-curing polymers canbe injected into the aneurismal sac to thrombose the blood in the sacand stop the blood flow between the lumbar arteries.

There is a clear need to manage Type II endoleaks. The current inventionproposes a novel design of a stent graft that eliminates Type IIendoleaks at the time of stent graft placement.

SUMMARY OF SOME EMBODIMENTS

Some embodiments described herein are directed to systems, methods andapparatuses for treating endovascular aneurysms or other endovasculardefects such as Type II endoleaks (collectively referred to as“defects”). However, it will be appreciated that the systems, methodsand apparatuses disclosed herein can be used in other fields or otherportions of the body.

In some embodiments, such defects can be treated with a deploymentsystem for deploying an endoluminal prosthesis within a passagewaycomprising a graft supported in a first position within a catheter and astent supported in a second position within the catheter and configuredto be expandable within the graft, wherein the first position does notoverlap the second position. The stent can be self-expandable, balloonexpandable, or expandable by other suitable means.

Some embodiments disclosed herein are directed to a stent graft systemcomprising a first stent graft having a first stent, a first inner graftsupported by the first stent, a second inner graft supported by thefirst stent, and an outer graft. In some embodiments, the second innergraft can be spaced apart from the first inner graft so that a portionof the first stent is not covered by either the first inner graft or thesecond inner graft. A first portion and a second portion of the outergraft can be attached to the first stent, the outer graft beingunsupported by the stent between the first and second portions so as toform a fillable space between the outer graft, the first inner graft,and the second inner graft. The stent graft system can further comprisea second stent graft deployable within the inside of the first stentgraft so as to sealingly cover the uncovered portion of the first stent,the second stent graft having a second stent and a second graft and alength that is greater than a length of the uncovered portion of thefirst stent graft.

Some embodiments disclosed herein are directed to a stent graft systemcomprising a stent having a flow lumen therethrough, a first inner graftsupported along at least a portion of the length of the stent, one ormore openings formed through a wall of the first inner graft, one ormore flap members configured to selectively cover the one or moreopenings formed through a wall of the first inner graft, and an outergraft positioned around the stent and configured to cover at least theone or more openings formed through the wall of the first inner graft.In some embodiments, the stent graft can be configured such that asubstantially sealed space can be created between the outer graft and atleast the first inner graft and the one or more flap members. The one ormore flap members can be configured to permit blood to flow from thelumen through the openings into the space, and to at least inhibit theflow of blood from the space through the openings and into the lumen.

Some embodiments disclosed herein are directed to a method of treating ablood vessel with a stent graft, comprising positioning a first stentgraft across the segment of the blood vessel to be treated, the firststent graft having a first stent, an inner graft having a first portionand a second portion, and an outer graft, filling the space between theinner graft and the outer graft through the uncovered portion of thestent with blood so that the outer graft expands outwardly away from theinner graft, and deploying a second stent graft inside the first stentgraft so as to sealingly cover the uncovered portion of the first stentgraft, the second stent graft having a second stent and a second graft.In some embodiments, the second portion of the inner graft can be spacedapart from the first portion of the inner graft so that a portion of thefirst stent can be uncovered by the inner graft, and a first portion anda second portion of the outer graft can be attached to at least one ofthe first stent and the inner graft. The outer graft can be unsupportedby the first stent or inner graft between the first and second portionsof the outer graft so as to create a fillable space between the outergraft and the inner graft.

Some embodiments disclosed herein are directed to a method of sealing abranch vessel with a stent graft, comprising positioning a first stentgraft across the segment of the blood vessel to be treated, the firststent graft having a first stent, an inner graft having a first portionand a second portion, and an outer graft, filling the space between theinner graft and the outer graft through the uncovered portion of thestent with blood so that the outer graft expands outwardly away from theinner graft and covers an ostium to a branch vessel, and deploying asecond stent graft inside the first stent graft so as to sealingly coverthe uncovered portion of the first stent graft, the second stent grafthaving a second stent and a second graft. In some embodiments, thesecond portion of the inner graft can be spaced apart from the firstportion of the inner graft so that a portion of the first stent isuncovered by the inner graft. Further, a first portion and a secondportion of the outer graft can be attached to at least one of the firststent and the inner graft, the outer graft being unsupported by thefirst stent or inner graft between the first and second portions of theouter graft so as to create a fillable space between the outer graft andthe inner graft.

Some embodiments disclosed herein are directed to a stent graft systemcomprising a stent, a first graft supported by the stent, and a secondgraft surrounding substantially all of an outside surface of the firstgraft. In some embodiments, the first graft is formed from a porousmaterial and is sized to cover at least a portion of the length of thestent. A first portion and a second portion of the second graft can beattached to the first stent, the second graft being unsupported by thestent between the first and second portions so as to form a fillablespace between the second graft and the first graft.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentdisclosure will now be described in connection with non-exclusiveembodiments, in reference to the accompanying drawings. The illustratedembodiments, however, are merely examples and are not intended to limitthe invention. The following are brief descriptions of the drawings,which may not be drawn to scale.

FIG. 1 illustrates an infrarenal abdominal aortic aneurysm.

FIG. 2 illustrates a stent graft placed in the abdominal aneurysm.

FIG. 3 illustrates type II endoleak after stent graft placement.

FIG. 4A illustrates an embodiment of a bifurcated stent graft used forthe treatment of abdominal aortic aneurysms, wherein the graft issupported by stent segments.

FIG. 4B illustrates an embodiment of a bifurcated stent graft used forthe treatment of abdominal aortic aneurysms, wherein the graft issupported by a bifurcated stent.

FIG. 5 illustrates an embodiment of a two-layer bifurcated stent graftused for the treatment of type II endoleaks.

FIG. 6 illustrates the embodiment of the two-layer bifurcated stentgraft illustrated in FIG. 5, placed in the abdominal aorta.

FIG. 7 illustrates the embodiment of the two-layer bifurcated stentgraft illustrated in FIG. 5, with the space between the two layers ofgraft filled with blood.

FIG. 8 illustrates the pressure distribution in the embodiment of thetwo-layer bifurcated stent graft illustrated in FIG. 5 after stent graftdeployment.

FIG. 9 illustrates the pressure distribution in the embodiment of thetwo-layer bifurcated stent graft illustrated in FIG. 5, after the spacebetween the two layers of graft is filled with blood.

FIG. 10 illustrates a healthy common iliac and hypogastric artery in anabdominal aortic aneurysm.

FIG. 11 illustrates an aneurysmal common iliac in an abdominal aorticaneurysm.

FIG. 12 illustrates an aneurysmal common iliac treated with anembodiment of a coiled member in the hypogastric artery and anembodiment of a stent graft into the external iliac artery.

FIG. 13 illustrates an aneurismal common iliac treated with anembodiment of a bifurcated stent graft with a two-layer iliac stentgraft segment.

FIG. 14 illustrates an embodiment of a bifurcated stent graft to treatan abdominal aortic aneurysm with a short proximal neck.

FIG. 15 illustrates an embodiment of a proximal extension placed in anembodiment of a bifurcated stent graft to treat an abdominal aorticaneurysm with a short proximal neck.

FIG. 16 illustrates another embodiment of a two-layer proximal extensionplaced in an embodiment of a bifurcated stent graft to treat anabdominal aortic aneurysm with a short proximal neck.

FIG. 17 illustrates another embodiment of a stent graft systemcomprising a first graft having two graft layers and a second graftacting as a sealing member.

FIG. 18 illustrates the placement of the embodiment of the graft systemfrom FIG. 17 into an aneurysm.

FIG. 19 illustrates another embodiment of a two-layer graft systemcomprising a bifurcated stent graft having two graft layers and a secondgraft acting as a sealing member.

FIG. 20 illustrates another embodiment of a stent graft system.

FIG. 21A illustrates some of the components of another embodiment of astent graft system, showing the components in an unassembled state.

FIG. 21B illustrates the embodiment of the stent graft system of FIG.21A, showing the components in the assembled state.

FIG. 22A illustrates some of the components of another embodiment of astent graft system, showing the components in an unassembled state.

FIG. 22B illustrates the embodiment of the stent graft system of FIG.22A, showing the components in the assembled state.

FIG. 23A is a perspective view of a portion of the layer or layerscomprising an embodiment of a porous or perforated inner graft.

FIG. 23B is a top view of a portion of the layer or layers comprisingthe embodiment of a porous or perforated inner graft of FIG. 23A.

DETAILED DESCRIPTION OF SOME EXEMPLIFYING EMBODIMENTS

This disclosure sets forth various embodiments of a novel stent graftsystem and method to reduce or eliminate Type II endoleaks. The designcan also be used to improve the seal of stent grafts in difficultanatomical situations. The following detailed description is nowdirected to certain specific embodiments of the disclosure. In thisdescription, reference is made to the drawings wherein like parts aredesignated with like numerals throughout the description and thedrawings.

Some embodiments described herein are directed to systems, methods, andapparatuses to treat Type II endoleaks, lesions, aneurysms, or otherdefects in the aorta, including, but not limited to, the thoracic,ascending, and abdominal aorta, to name a few. However, the systems,methods, and apparatuses may have application to other vessels or areasof the body, or to other fields, and such additional applications areintended to form a part of this disclosure. For example, it will beappreciated that the systems, methods, and apparatuses may haveapplication to the treatment of blood vessels in animals. In short, theembodiments and/or aspects of the endoluminal prosthesis systems,methods, and apparatuses described herein can be applied to other partsof the body or may have other applications apart from the treatment ofthe thoracic, ascending, and abdominal aorta. And, while specificembodiments may be described herein with regard to particular portionsof the aorta, it is to be understood that the embodiments described areadaptable for use in other portions of the aorta or other portions ofthe body and are not limited to the aortic portions described.

FIG. 1 illustrates an infrarenal abdominal aneurysm. The aorta 4 isenlarged below the renal arteries 2 a, 2 b and above the iliac arteries3 a, 3 b. The enlarged aorta forms an aneurysm sac 1. Pairs of lumbararteries 5 a, 5 b branch from the aorta 4 in the region of the aneurysmsac 1. FIG. 2 shows a bifurcated stent graft 10 placed in the aorta 4 toexclude the aneurysm sac 1 from the arterial blood pressure. FIG. 3illustrates a leakage flow from a first pair of lumbar arteries 5 a to asecond pair of lumbar arteries 5 b wherein the blood pressure in thefirst pair of lumbar arteries 5 a is greater than that in the secondpair of lumbar arteries 5 b. This type of leak is referred to as Type IIendoleak.

FIG. 4 shows a typical stent graft 20 for the treatment of abdominalaortic aneurysms. The stent graft system can be a single piecebifurcated stent graft or a modular stent graft comprising two or moreindividual stent grafts that are assembled in situ. The stent graft 20can consist of a main body 21 and two branch grafts 22 a, 22 b. Thestent graft can have individual stent segments 23, as illustrated inFIG. 4A, or a bifurcated stent 24, as illustrated in FIG. 4B. The stent24 or stent segments 23 can be self expandable, balloon expandable, orcan be other similar or suitable stents. The graft 21 can be made frompolyester, PTFE, ePTFE, or any other suitable material.

FIG. 5 illustrates an embodiment of a two-layer bifurcated stent graft30 used for the treatment of type II endoleaks. The basic constructionof the stent graft 30 can be similar to that of any existing stent graftsystem having a main body 31, branch grafts 32 a, 32 b, stent segments33, and a first inner graft cover 34. In some embodiments, the main bodyof the bifurcated stent graft can have a second, outer graft cover 35.The outer graft cover 35 can be made from the same material as the innergraft 34. In some embodiments, the outer graft cover 35, or any otherouter graft embodiments disclosed herein, can have one or moreradiopaque markers thereon to provide visualization of the position orlevel of inflation of the outer graft cover during deployment.Similarly, any of the stent or other graft embodiments disclosed hereincan have one or more radiopaque markers thereon to provide visualizationof the position of such prostheses during deployment.

The diameter of the outer graft cover 35 can be larger than that of theinner graft cover 34. In some embodiments, the outer graft cover 35 orany other outer graft cover embodiment disclosed herein can have atubular shape, or can have a bulged middle portion such that the middleportion defines a greater diameter than the end portions of the outergraft cover 35. In some embodiments, the diameter of the outer graftcover 35 can be sufficiently large to expand to the flow lumen oragainst the inside surface of the aneurysm. The inner graft cover 34 andthe outer graft cover 35 can be connected at the distal and proximalends to form a sealed space 36. One or more openings 37, which can haveany suitable size, large or small, can be cut or otherwise formed in theinner graft cover 34 to allow fluid communication between the innerlumen of the stent graft and the space 36.

In the embodiment described in FIG. 5, the opening in the inner graftlayer can provide fluid communication between the inner lumen of thegraft and the space between the inner graft layer and the outer graftlayer. Preferably, the opening can be large enough to allow blood cellsto enter the space. At the same time, the opening can be small enough toprevent flow patterns to form in the space that would delay bloodcoagulation. In some embodiments, the size of the opening can be between20 μm and 5 mm. In some embodiments, the size of the opening can bebetween 100 μm and 2 mm. There can be one opening or multiple openings.The opening can be in form of holes punched into the graft material orin form of porous graft material (such as, without limitation, PTFE,ePTFE, polyester, or other suitable materials) with pore sizessufficiently large to allow blood to enter the space between the innerand outer graft layer. Alternatively, the inner graft can be made from aporous metal. In some embodiments, a braided stent can form the innergraft. The gaps between the braids can allow blood to enter the space.The braided stent would eliminate the need for a separate stent tosupport the inner graft. The braided stent can be constructed frommemory metals or memory plastics, or any other suitable material ormaterials.

Further, in some embodiments, the inner graft can be a generallynon-porous material having a plurality of openings formed therein alongat least a portion, or all of, the length of the inner graft layer. Insome embodiments, as will be described in greater detail below, theinner graft layer can have pores or openings that are configured toallow one directional fluid flow. For example, the pores or openings canpermit fluid to flow from an inside lumen through the inner graft,through the openings or pores in the inner graft layer, and into thespace between the inner and outer graft layers, while being configuredto prevent the flow of fluid (e.g., blood) from flowing in the oppositedirection. Any of the embodiments of the graft layers disclosed herein,including the inner graft layer described above, can be used with any ofthe stent graft embodiments described in this application. For example,in some embodiments, the porous or perforated inner graft layerdescribed herein can be used with any of the stent or stent graftembodiments disclosed herein with appropriate modifications, asnecessary. All of such combinations are contemplated as forming a partof this disclosure.

In some embodiments, the inner graft material can be configured suchthat the pores or openings thrombose after a particular duration ofexposure to a patient's blood. In this arrangement, the pores oropenings in the inner graft material will essentially be sealed, so asto substantially inhibit or prevent the flow of blood through suchopenings or pores after the thrombosis of such openings or pores occurs.For example, the openings or pores can be configured to thrombose orbecome substantially sealed after the blood thinning agent (such asheparin) that is typically administered during arterial repair or othervascular procedures is removed or diminished from the patient's bloodstream, thereby sealing the blood within the space between the inner andouter grafts within such space.

In some embodiments, the circumference of the outer graft cover can belarger than that of the inner graft. The outer graft cover can be largeenough to inflate to the size of the flow lumen in the diseased bloodvessel. In some embodiments, a substantial portion of the outer graftcover can touch the wall of the blood vessel when inflated. In the caseof an abdominal aortic aneurysm, the diameter of the outer graft covercan be from approximately 4 cm or less to approximately 8 cm. In thecase of an iliac aneurysm, the diameter of the outer graft can be fromapproximately 2 cm or less to approximately 4 cm. In some embodiments,the outer graft cover can be configured to only cover a portion of theinner graft cover. In some embodiments, the outer graft cover can beconfigured to only cover the distal portion, the proximal portion, orthe mid-section of the inner graft cover. In some embodiments, the outergraft cover can be configured to only cover a portion of thecircumference of the inner graft cover.

FIG. 6 illustrates the embodiment of the two-layer bifurcated stentgraft 30 illustrated in FIG. 5, deployed in the abdominal aorta. Thestent graft 30 can be positioned proximally below the renal arteries 2 aand 2 b and distally in the iliac arteries 3 a and 3 b. The stent graft30 can seal the aneurysm 1 from the aorta 4. The inner graft cover 35can form a flow lumen for blood through the aorta. The outer graft cover36 can be initially collapsed onto the inner graft cover 35.

FIG. 7 illustrates the embodiment of the two-layer bifurcated stentgraft 30 illustrated in FIG. 5, with the space 36 between the two layersof graft filled with blood. As such, FIG. 7 shows the finalconfiguration of the embodiment of the two-layer bifurcated stent graft30 illustrated in FIG. 5. The blood in the aorta can enter through theopenings 37 into the space 36 between the inner graft cover 34 and theouter graft cover 35. In some embodiments, the blood can cause the outergraft cover to inflate until it substantially fills or approximatelycompletely fills the aneurysm sac. The blood in the space 36 canultimately coagulate and form a thrombus.

FIG. 8 illustrates the pressure distribution in the embodiment of thetwo-layer bifurcated stent graft 30 illustrated in FIG. 5 after stentgraft deployment. FIG. 9 illustrates the pressure distribution in theembodiment of the two-layer bifurcated stent graft 30 illustrated inFIG. 5, after the space between the two layers of graft is filled withblood. As such, FIGS. 8 and 9 illustrate the mechanism of inflation orexpansion of the outer graft cover. When the stent graft is placed inthe abdominal aorta, the aneurysm 41 can be isolated from the aorta 40as illustrated in FIG. 8. As a result, the pressure (Psac) in theaneurysm sac can drop. The pressure in the aorta (Paorta) is typically60 mmHg-200 mmHg. The isolated aneurysm sac can be pressurized antegradefrom the lumbar arteries. The pressure in the sac (Psac) is typically 30mmHg-50 mmHg immediately after stent graft placement. After stent graftplacement, the pressure in the aorta (Paorta) can push blood through theopenings 46 into the space 43 between the inner graft cover 44 and theouter graft cover 45. The pressure in the space (Pbag) can rise abovethe sac pressure (Psac) and the outer graft 45 cover can inflate andexpand approximately against the wall of the sac 41, displacing theblood in the sac 41. During the filling phase, the pressure in the space(Pbag) can be lower than the aortic pressure (Paorta) but higher thanthe sac pressure (Psac).

FIG. 9 illustrates the completed filling of the space 43. Once the outergraft cover 45 is fully inflated, the pressure in the space 43 can beapproximately the same as the pressure in the aorta 41. Blood flowthrough the opening or openings 46 can thereafter be significantlyreduced or can cease. The blood in the sac 41 can be completelydisplaced. The blood in the space 43 can be stagnant and can coagulate,forming thrombus. Once the thrombus is formed, the solid thrombus in thespace 43 can isolate the pressure between the aorta and the aneurysmwall so that the aneurysm sac can be isolated from the aortic pressure.

Therefore, in some embodiments, a branch vessel adjacent to the outergraft layer 45 (for example, a lumbar or mesenteric artery) canfacilitate the expansion of the outer graft layer against the insidesurface of the vessel wall by reducing the pressure (Psac) within thespace between the outer graft material and the vessel wall relative tothe pressure within the aorta (Paorta). In this configuration, in someembodiments, the space 43 between the inner and outer layers can fillwith blood from the aorta as the branch vessel reduces the pressurebetween the outer graft layer and the vessel wall, such that anadditional instrument or medically administered injection of blood orfluid into (i.e., pressurization or inflation of) the space 43 may beavoided.

Type II endoleaks, as illustrated in FIG. 3, can be suppressed oreliminated by the expanded outer graft cover. The lumbar arteries 5 a, 5b in FIG. 3 can be covered by the outer graft cover 45. Withoutlimitation, one advantage of some embodiments of the proposed design isthat the aneurysm sac can be filled and Type II endoleaks can besuppressed without the need for any additional procedural steps aboveand beyond the standard steps required to deploy a stent graft in theabdominal aorta. Furthermore, in some embodiments, no foreign materialis needed to be introduced into the body or the prosthesis to embolizethe sac.

The concept of a second outer graft layer can also be applied to thestent grafting of challenging anatomies in which is it difficult toobtain a seal between the graft and the vessel wall. For example, theblood vessel may have local calcium deposit, thrombus, or sudden changesin the diameter. The stent connected to the inner graft layer may notallow the inner graft to continuously contact the wall along the sealline. In the following disclosure, additional embodiments and examplesare presented to illustrate further benefits of the second outer graftlayer configuration.

FIG. 10 shows an abdominal aneurysm with the two common iliac arteries51 a and 51 b branching from the aneurismal aorta 50. The common iliacartery 51 a branches into the hypogastric artery 52 and the externaliliac artery 53 about 3 cm-8 cm from the bifurcation.

FIG. 11 shows an abdominal aneurysm with one diseased common iliacartery 61 b. The common iliac artery 61 b is enlarged. An enlargedcommon iliac artery may compromise the distal seal when stent graftingthe aneurysm. Specifically blood may flow from the hypogastric artery 62into the aneurysm sac 60, thereby pressurizing the sac.

FIG. 12 illustrates an aneurismal common iliac treated with anembodiment of a coiled member 72 in the hypogastric artery and anembodiment of a stent graft 70 into the external iliac artery. As such,FIG. 12 illustrates one strategy to stent graft an abdominal aneurysmwith one diseased common iliac artery as shown in FIG. 11. First, insome embodiments, the hypogastric artery 62 can be embolized. This canbe accomplished by placing the coiled member 72 in the hypogastricartery 62. Alternatively, an alternative form of a plug can be deployedin the hypogastric artery 62. After embolization of the hypogastricartery 62, in some embodiments, a stent graft 70 can be placed in theaneurysm 60, the stent graft 70 having an extended branch graft 71 thatcan extend into the external iliac artery 63 to provide a distal seal.

FIG. 13 illustrates an alternative strategy for the endovasculartreatment of the abdominal aneurysm with one diseased common iliacartery as shown in FIG. 11. The stent graft 80 can have a branch graft81 with a two-layer graft cover described in FIG. 5. The arterialpressure can inflate the outer graft cover 82 and the outer graft 82 cancover and seal the hypogastric artery 62 and at least partially fill thediseased portion of the common iliac artery 61 b. The concept can worksimilar to the occlusion of the lumbar arteries in the aneurysm sac. Theproposed strategy can eliminate the need for coiling, which often has tobe done in a separate procedure prior to stent grafting.

FIGS. 14-16 illustrate another application of the two-layer graft cover.FIG. 14 shows a bifurcated stent graft 100 placed onto the anatomicalbifurcation 93 for stent grafting of an abdominal aortic aneurysm 90.The bifurcated device 100 can provide a platform for subsequent graftplacement at the aortic neck 92. In FIG. 15, an embodiment of a tubularstent graft extension 101 can be placed to overlap with the bifurcatedstent graft 100 and seal the aneurysm below the renal arteries 91 a and91 b. Distance between the renal arteries and the aneurysm sac is oftenreferred to as the proximal neck 92, and the distance between theproximal end of the stent graft 101 and the aneurysm sac 90 is oftenreferred to as the proximal seal zone. It can be preferred to place theproximal end of the stent graft 101 right below the renal arteries 91 aand 91 b to maximize the length of the proximal seal zone. In short-neckaneurysms, the potential seal zone may be too short to provide anadequate seal. Commercially available stent graft systems typicallyrequire a neck length of at least 10-15 mm to ensure a proper proximalseal.

FIG. 16 shows an embodiment of a two-layer stent graft extension 110placed in the proximal neck 92 of the aortic aneurysm 90. The inflatedouter layer 111 can extend the contact length 112 between the stentgraft 110 and the aortic wall into the aneurysm sac 90 effectivelyincreasing the proximal seal zone.

FIG. 17 illustrates another embodiment of a stent graft system 118,which can be a two-layer stent graft system. The stent graft system canbe tubular, bifurcated The graft system 118 can comprise a first stentgraft 120, which can have a tubular stent 121 and one or more tubularinner graft or graft segments 122 that partially cover the stent 121.With reference to FIG. 17, some embodiments of the stent graft system118 can have a first inner graft 122 a and a second inner graft 122 bthat can be positioned adjacent to the end portions of the stent 121. Insome embodiments, the first inner graft 122 a and a second inner graft122 b can be spaced apart so that a portion of the stent 121 can beuncovered by the inner graft 122. For example, without limitation, aportion of the midsection 124 of the stent 121 can be uncovered. Eitheror both of the first inner graft 122 a and a second inner graft 122 bcan be positioned on an inside surface of the stent 121 (asillustrated), or can be positioned on an outside surface of the stent121.

An outer graft cover 123 can be connected to or otherwise supported bythe stent 121 at one or both ends. The outer graft cover 123 can have aconstant diameter, or can have a varying diameter along a lengththereof. In some embodiments, the middle portion of the outer graftcover 123 can define a larger diameter than one or more of the endportions of the outer graft cover 123. In some embodiments, the diameterof some or all of the outer graft cover 123 can be greater than thediameter of the first inner graft 122 a and/or second inner graft 122 b.The uncovered midsection 124 can provide for rapid filling of the outergraft cover 123 with the patient's blood, as is illustrated in FIG. 17.A second stent graft 125 can be placed inside the first stent graft 120to seal the space created between the outer graft cover 123 and theinner graft 122. The graft 127 of the second stent graft 125, the innergraft 122 and the outer graft 123 of the first stent graft 120 can forma sealed space in which the patient's blood can be trapped.

FIG. 18 illustrates the placement of the stent graft system 118 in ananeurysm 131 of the aorta 130. When the first stent graft 120 is placedover the aneurysm sac 131, the blood pressure in the aorta 130 can forceblood into the space 132 and can inflate the outer graft cover 123. Thesecond stent graft 125 can be placed inside the first stent graft 120and can be configured to substantially or completely seal the space 132.

FIG. 19 illustrates another embodiment of a stent graft system 138. Thefirst stent graft 140 can be a bifurcated stent graft for the treatmentof aorto-iliac aneurysms. In some embodiments, the embodiment of thestent graft system 138 can have any of the same features, components, orother details of any of the other embodiments of stent graft systemsdisclosed herein. In some embodiments, the second stent graft 141 can bea straight tubular stent graft. One advantage of the system comprisingtwo stent grafts is that the space inside the outer graft cover can fillrapidly. Apertures or other small openings in the inner graft cover mayreduce the flow into the space. They may also clog or get obstructed byemboli and thrombus. Another advantage is that the second stent graftcan provide an instantaneous seal. In case of apertures or smallopenings, blood exiting the sac during the coagulation phase may formemboli or thrombus. Another advantage is the ability to inject contrastmedium into the space to verify inflation of the outer graft cover.

The concept of a second stent graft can also be applied to theembodiments described herein with regard to, without limitation, FIGS.5, 13, and 15. The second stent graft can be placed to cover thesegments of the first stent graft that contains the openings for theblood to enter into the outer graft layer.

FIG. 20 illustrates another embodiment of a stent graft system 148,which can be a two-layer stent graft system. In some embodiments, thestent graft system 148 can have any of the components, features, orother details of any of the other stent graft system embodimentsdisclosed herein, including without limitation the stent graft system118 described above.

With reference to FIG. 20, the graft system 148 can comprise a firststent graft 150, which can have a tubular stent 151 and one or moretubular inner graft or graft segments 152 that partially cover the stent151. A portion 154 of the stent 151 can be uncovered. In someembodiments, the uncovered portion 154 of the stent 151 can be locatednear an end portion of the stent 151. An outer graft cover 153 can beconnected to or otherwise supported by the stent 151 at one or bothends. The uncovered portion 154 can provide for rapid filling of theouter graft cover 153 with the patient's blood. A second stent graft 155can be placed inside the first stent graft 150 to seal the space createdbetween the outer graft cover 153 and the inner graft 152. In someembodiments, the second stent graft 155 can be placed inside the firststent graft 150 after the outer graft cover 153 has been sufficientlyfilled with blood. The graft 157 of the second stent graft 155, theinner graft 152 and the outer graft 153 of the first stent graft 150 canform a sealed space in which the patient's blood can be trapped.

In some embodiments, the outer graft cover 153 can be placed on theoutside of the stent 151 and inverted at the ends to partially cover theinside of the stent 152. The open stent segment 155 can be located closeto one end of the stent graft system. In some embodiments, the outergraft cover 157 can be configured to only form a hem at one end of thestent 151.

FIG. 21A illustrates some of the components of another embodiment of astent graft 180, showing the components in an unassembled state. FIG.21B illustrates the embodiment of the stent graft 180 of FIG. 21A,showing the components in the assembled state. With reference to FIGS.21A and 21B, the stent graft system 180 can have a graft 181 and a stent182, and can have one or more flow valves therein configured to allowflow of fluid through said valves or openings in only one direction. Thestent graft system 180, or any other stent graft system disclosedherein, can have a bifurcated stent graft (as illustrated), a tubularstent graft (not illustrated), or any other suitable configuration of astent graft, such as curved, tapering, or otherwise.

The bifurcated graft 181 can have a main graft body portion 184, a firstgraft branch portion 185, and a second graft branch portion 186.Similarly, the stent 182 can have a main stent body portion 187, a firststent branch portion 188, and a second stent branch portion 189. Thestent 182, or any other stent embodiment disclosed herein, can providesubstantially continuous scaffolding along the length thereof, or can beformed in segments or discrete portions that can be interconnecteddirectly to other stent segments portions or can be held in the desiredposition by attachment to the graft material. In some embodiments, thestent 182, or segments or portions thereof, can be sutured or otherwiseattached to the graft 181. In some embodiments, as in the illustratedembodiment, the proximal portion 182 a of the stent 182 can extendproximal to the proximal end 181 a of the graft 181 so that suchproximal portion 182 a of the stent 182 is not covered by the graft 181.

One or more openings 190 can be formed in the graft 181. In theillustrated embodiment, one opening 190 is formed laterally through aside wall of the main graft body portion 184 of the graft 181. Theopening 190 can be formed in any desired position of the graft 181. Asillustrated, in some embodiments, the opening 190 can be positioned sothat blood can flow through the one or more opening 190, similar to theopenings 37 described above with reference to FIGS. 5 and 6. The openingor openings 190, or any other openings disclosed herein, can bepositioned in the graft 181 so as to be positioned between the struts,wires, or other members of the stent which the graft covers.

With reference to FIG. 21A, the stent graft system 180, or any otherstent graft system disclosed herein, can have a second graft member 200having a tabbed or flap portion 202 (also referred to herein as a flapmember, valve cover, or just cover). As will be discussed in greaterdetail, the openings 190 and covers 202 can form single directional flowvalves to permit flow into the space surrounding the graft 184 andsecond graft member 200. The second graft member 200 can have a tubularshape and can be configured to surround at least a portion of the lengthof the stent 182 around all or a portion of the circumference of thestent 182. As illustrated in FIG. 21B, the second graft member 200 canbe configured to be positioned over the outside surface of the proximalportion 182 a of the stent 182, and can be sized and configured so thatthe tabbed portion 202 can cover the opening 190. In some embodiments,the second graft member 200 can be sutured or otherwise attached to thegraft 181. For example, without limitation, the second graft member 200can be fixed to the graft 181 using one or more sutures 206circumferentially positioned around the stent graft system 180, asillustrated in FIG. 21B.

In some embodiments, the flap member 202 can be formed on or affixed tothe main graft body portion 184 of the graft 181. Without limitation,the flap member 202 can cover a portion of the length of the stent 182and all or a portion of the circumference of the stent 182. In somearrangements, the flap member 202 can be stitched, sutured, adhered, orotherwise attached to the outside surface of the main graft body portion184 of the graft 181.

An outer graft member 212 can be positioned over an outside surface ofthe main graft body portion 184 and the second graft member 200. Theouter graft member 212 can be sealingly fixed to the main graft bodyportion 184 and the second graft member 200 so that a substantiallysealed space 214 is created between the outer graft member 212 and themain graft body portion 184 and/or the second graft member 200. Thestent graft system 180 can be configured so that blood can pass from theinside of the main graft body 184 through the opening 190 and into thespace 210 formed inside the outer graft member 212, but so that thetabbed portion 202 inhibits or substantially prevents blood from flowingfrom the space 214 back through the opening 190.

In this arrangement, similar to other embodiments described above, bloodin the aorta can pass through the openings 190 into the space 214 formedinside the outer graft member 212, causing the outer graft cover 212 toinflate until it substantially fills or approximately completely fillsan aneurysm sac. The blood in the space 214 can ultimately coagulate andform a thrombus.

The graft 181, second graft member 200, the outer graft member 212, orany other graft embodiment disclosed herein can be formed from PTFE,ePTFE, or any other suitable material. The stent 182, or any other stentembodiment disclosed herein, can be formed from Nitinol, stainlesssteel, a shape memory or heat activated material, or any other suitablematerial. The stent 182, or any other stent embodiment disclosed herein,can be self-expandable, balloon expandable, or expandable by any othermechanical or other means such as, without limitation, heat.

FIG. 22A illustrates some of the components of another embodiment of astent graft 180′, showing the components in an unassembled state. FIG.22B illustrates the embodiment of the stent graft 180′ of FIG. 22A,showing the components in the assembled state. With reference to FIGS.22A and 22B, the stent graft system 180′ can have a graft 181′ and astent 182. The stent graft system 180′ can have any of the samefeatures, configurations, or other details of the stent graft system 180described above, except as described below.

With reference to FIGS. 22A, 22B, the main graft body portion 184′ ofthe graft 181′ can have two or more openings 190′ formed therein (twoopenings 190′ being illustrated). Additionally, the second graft member200′ can have a tabbed or flap portion 202′ that can be configured tocover each of the two or more openings 190′. Although not required, insome embodiments, the tabbed portion 202′ can have a slit 203′ betweenthe portions of the tabbed portion 202′ that cover each of the openings190′.

FIG. 23A is a perspective view of a portion of the layer or layerscomprising an embodiment of a porous or perforated inner graft 230. FIG.23B is a top view of a portion of the layer or layers comprising theembodiment of a porous or perforated inner graft 230 of FIG. 23A. Insome embodiments, with reference to FIGS. 23A, 23B, the inner graft 230can have a base layer 232 and an outer layer 234 and one or more flowdirection valve members, as will be described in greater detail. In someembodiments, the base layer 232 can be porous or otherwise pervious, orcan be impervious and define a plurality of openings therethrough. Thebase layer 232 can be made from PTFE, ePTFE, polyester, or any othersuitable material, and can be woven, wrapped or otherwise formed from asheet, or otherwise. In some embodiments, the base layer 232 can besubstantially impervious, and the tubules 238 and openings 240 can beformed directly in the base layer 232.

The outer layer 234 can be formed from a substantially or completelyimpervious material having one or more channels or tubules 238projecting away from the base layer, the tubules 238 each having anopening 240 in a distal end 238 a thereof. The tubules 238 can be formedfrom a thin cylinder or cone of material so that the walls of saidtubules 238 are tapered. The tubules 238 can be configured to permitfluid flow therethrough in only one direction (for example, in thedirection indicated by arrow “F” in FIG. 23A), and can be configured toprevent or substantially inhibit the flow of fluid (such as blood) inthe opposite direction. For example, as discussed above, the tubules 238can be formed on an outside surface of any embodiments of the innergraft disclosed herein so as to project outwardly away from the outsidesurface of the inner graft 230. In some embodiments, the outer layer 234can cover substantially all of the porous or pervious base layer 232 sothat substantially the entire inner graft 230 comprises one-way flowcontrol.

The tubules 238 can have a thickness (represented by “T” in FIG. 23B),opening diameter or size (represented by “D” in FIG. 23A), and height(represented by “H” in FIG. 23B) configured such that the tubules 238collapse or otherwise substantially close when a fluid pressure actingagainst an outside surface 242 of the inner graft 230 is greater than afluid pressure acting against an opposite, inside surface of the innergraft. The material chosen for the film or outer layer 232 (or the innerlayer 234 if the tubules 238 are formed therein) can affect the optimalthickness T, diameter D, and/or height H of the tubules 238.

In some embodiments, the diameter or size D of the openings 240 canrange from approximately 20 μm or less to 2 mm or more, and can have aheight H from approximately one half of the diameter D to 5 times thediameter D, and a thickness T from approximately 2 μm or less toapproximately 100 μm or more. Further, depending on the desired flowrate through the inner graft 230 and number of tubules 238 formed in theinner graft 230, the tubules 238 can be spaced apart by distance “L”shown in FIG. 23B that can range from approximately 120 μm or less toapproximately 5 mm or more.

Thrombosis of the blood in the space between the inner graft cover andthe outer graft cover can stop or significantly reduce the communicationof the pressure in the flow lumen to the vessel wall. The blood in thespace can coagulate and thrombose once the blood is stagnant. Thecoagulation process can be accelerated by placing a thrombotic agentinto the space between the inner and outer graft cover. Suitable agentscan include, but are not limited to, salts, silk, albumin, and fibrin.The agents can be placed in the space in powder form or coating of theinner surfaces of the inner and outer graft cover. The opening into thespace can be treated with a thrombotic agent to seal off the openingafter the outer graft cover has been inflated. For example, a section ofthe inner graft cover can be made from a woven or knitted porous silkfabric.

Although the inventions have been disclosed in the context of apreferred embodiments and examples, it will be understood by thoseskilled in the art that the present disclosure extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. In addition, while a number of variations of the invention havebeen shown and described in detail, other modifications, which arewithin the scope of this invention, will be readily apparent to those ofskill in the art based upon this disclosure. It can be also contemplatedthat various combinations or subcombinations of the specific featuresand aspects of the embodiments can be made and still fall within thescope of the invention. Accordingly, it should be understood thatvarious features and aspects of the disclosed embodiments can be combinewith or substituted for one another in order to form varying modes ofthe disclosed invention. Thus, it can be intended that the scope of thepresent disclosure herein disclosed should not be limited by theparticular disclosed embodiments described above.

What is claimed is:
 1. A method of treating a segment of a blood vesselwith stent grafts, comprising: positioning a first stent graft acrossthe segment of the blood vessel to be treated, the first stent grafthaving a first stent, an inner graft having a first portion and a secondportion, and an outer graft; wherein: the second portion of the innergraft is spaced apart from the first portion of the inner graft so thata portion of the first stent is uncovered by the inner graft; and afirst portion and a second portion of the outer graft are attached to atleast one of the first stent and the inner graft, the outer graft beingunsupported by the first stent or inner graft between the first andsecond portions of the outer graft so as to create a fillable spacebetween the outer graft and the inner graft; allowing the space betweenthe inner graft and the outer graft to fill through the uncoveredportion of the stent with blood so that the outer graft expandsoutwardly away from the inner graft; and deploying a second stent graftinside the first stent graft so as to sealingly cover the uncoveredportion of the first stent graft, the second stent graft having a secondstent and a second graft.
 2. The method of claim 1, wherein the outergraft supports one or more radiopaque markers thereon.
 3. The method ofclaim 1, further comprising monitoring a level of inflation of the outergraft before deploying the second stent graft inside the first stentgraft.
 4. The method of claim 1, wherein the second stent graft has alength that is greater than a length of the uncovered portion of thefirst stent.
 5. The method of claim 1, wherein blood fills the spacebetween the inner graft and the outer graft when the first stent graftis positioned in the blood vessel.
 6. The method of claim 1, furthercomprising allowing the blood to thrombose in the space after placementof the first stent graft.
 7. The method of claim 1, wherein the outergraft expands outwardly against an inside surface of the blood vessel.8. The method of claim 1, wherein the first stent graft is bifurcated.9. The method of claim 1, wherein the outer graft expands outwardly awayfrom the inner graft and covers an ostium to a branch vessel.